The purpose of this article is to give an account of Franceso Patrizi da Cherso's (1529-1597) criticism and eventual refutation of the Aristotelian principles of form, privation, and matter, as it can be found in his voluminous anti-Aristotelian treatise, the Discussziones Peripateticae (1581). His refutation of these three concepts is informed by two convictions: (i) that Aristotle's theory is inconsistent, and can therefore not be taken seriously as a relevant contribution to philosophical discussion; (ii) that Aristotle's theory, whether consistent or not, is either unoriginal or unintelligible, and must therefore be rejected by philosophers worthy of this name anyway. Patrizi's argumentation is conducted with great philological care and philosophical acumen. He tries to prove that there is no need for principles to be finite; that they cannot be everlasting; that they cannot be generated from one another; and that there is no need for them to be contraries. He further tries to show that neither privation nor form can be principles, the rejection of form including the notions of form as universal, as particular, as individual, and as generic, as well as those of form as nature and of form as cause. Patrizi concludes that forms must be accidents. Although prime matter is retained as a principle, it is severely qualified; this is here interpreted with reference to Patrizi's own theory of principles in the Nova de universis philosophia. The article concludes with a brief outlook on the influence (or rather, lack of influence) of Patrizi's discussion and suggests one possible explanation for it.